Norway? Oslo, Norway?

First someone blew up a bomb in Oslo today, now come reports of a gunman opening fire, just North of there. What on Earth is going on? In the early article I read, they said this, too: "There was no clear claim of responsibility and while the attacks appeared to bear the hallmarks of an Islamist militant assault, analysts said it was too early to draw any conclusions." Wait. First, what are "the hallmarks of an Islamist militant assault" and second, isn't that statement itself, drawing conclusions? Link: http://news.yahoo.com/explosion-rocks-central-oslo-norway-pms-office-134903379.html